Zimbabwe's Robert Mugabe has said he now accepts President Emmerson Mnangagwa as the country's legitimate leader after initially accusing him of leading a "disgraceful" de facto coup that ended his near four-decades rule last year.

On the eve of the July 30 vote, Mugabe said he would vote for the opposition to remove Mnangagwa's "military government", as the 94-year-old leader expressed bitterness and turned against his one-time allies in the ruling ZANU-PF party.

But at a funeral wake of his mother-in-law, Mugabe said Mnangagwa's victory, which is still disputed by his main opponent Nelson Chamisa, made him a legitimate president, the privately-owned NewsDay and State-owned The Herald newspapers reported on Friday.

"The wrong that happened last November has been erased by his victory in the July 30 elections. We now have a government born out of the constitution. I now accept his leadership and he now deserves the support of every Zimbabwean," Mugabe said, looking frail in video footage on an online television site.

"Before the elections, I did not support him because he came through illegal means which violated our liberation values that politics lead the gun," added Mugabe, likely ending the feud between the new president and his former mentor.

Mugabe's forced resignation divided ZANU-PF and created mistrust between the army on one side and the police and intelligence agency on the other, but the rapprochement could help overcome those differences and rally others behind Mnangagwa.

The military last year intervened after expulsions of ZANU-PF officials that were sympathetic to Mnangagwa, then Mugabe's deputy, and to stop the presidential ambitions of the wife of the veteran former leader.

Mugabe's wife Grace and a ZANU-PF faction known as G40 had been resisting Mnangagwa's rise to power. Mugabe again denied that he had planned to install Grace as his preferred successor, NewsDay and The Herald reported on Friday.

At the wake Grace also said people should pray for her husband, who she said was not feeling well. The couple have travelled to Singapore several times this year for Mugabe's medical treatment.